As the functions of portable equipment, such as a cellular phone or a digital camera, become more sophisticated and the market for the portable equipment expands, a necessity for displaying a wide variety of characters on a display device of the portable equipment becomes greater. Character codes are assigned to respective characters, and the character codes include various types of codes, such as JIS kanji codes, Unicodes, and so forth. There are many cases where Unicodes—two-byte codes being allocated to all characters in order to address a plurality of languages—are used.
When characters are displayed on the display device, it is better to prepare beforehand a table, where start addresses and character codes of bitmap data are brought into a one-to-one correspondence; to take an input character code as a key and retrieve a start address corresponding to that character code from this table; and to read bitmap data from the start address, which has been acquired through the retrieval; and display the thus-read bitmap data.
FIG. 10 shows an example conventional search table. Character codes are represented in hexadecimal, and a character code and a start address of bitmap data corresponding thereto are stored, in one-to-one correspondence, in each record of the table. When a character code is input from a higher-level device, a processor performs sequential retrieval of a start address corresponding to the character code from the top of the table.
Japanese Patent 3,240,673 describes dividing a search table according to a code system of a character code.
However, a configuration for making a retrieval while taking a character code as a key, such as that shown in FIG. 10, has a problem of a necessity for sequential retrieval from the top of the table in order to obtain a start address of the input character code as well as a problem of consuming much time before the finally-input character is displayed on the display device. As a matter of course, when the range of supported character codes is narrow, such a system does not pose any problem. However, in the case of character codes which support a plurality of languages, the range of the character codes becomes enormous, and hence retrieval speed drops drastically. In a case where large amounts of characters are displayed simultaneously on the screen of a digital camera, or the like, a retrieval time required to render one character must be reduced to a minimum, and such a drop in retrieval speed is not desirable. Moreover, in consideration of an application of portable equipment, the memory capacity used for storing a table must be minimized, to thus effectively utilize system resources.